Cellulose Filaments are one type of cellulose fibre made in a mechanical process in an aqueous suspension without the use of chemicals or enzymes. In this process, cellulose fibres (typically softwood kraft fibers) are split along their longest axis into over 1,000 Cellulose Filaments. The resulting Cellulose Filaments have similar fibre length and a high aspect ratio (e.g. a fibre length between 100 μm and 2,000 μm and a width between 30 nm and 500 nm). Typical solids levels for the finished product aqueous suspension of Cellulose Filaments generally range from 25% to 45% (most commonly ˜30%).
Cellulose Filaments are very hydrophilic and can be easily dispersed in water. Cellulose Filaments have a high density of —OH (hydroxyl) groups on their surface resulting in a strong tendency to form hydrogen bonds with each other. Uncontrolled drying of Cellulose Filaments leads to solid Cellulose filaments “blocks” that are non-dispersible. However, due to their high surface area, strength characteristics, size and aspect ratio, Cellulose Filaments are an excellent candidate for making lightweight composite materials.
Recently, the use of natural fibers such as cellulose as reinforcing agents in polymer composite materials has become of great interest. Natural cellulose-based fibers have the advantage of being low-cost, biodegradable, renewable, low density (compared to glass and other synthetic fibers) and high specific stress and modulus.
However, natural fibers such as cellulose are generally not compatible with a hydrophobic polymer matrix. Rather, natural fibres such as cellulose tend to be hydrophilic and therefore form aggregates during processing with hydrophobic polymer matrices. For example, due to this lack of compatibility with hydrophobic matrices, incorporation of hydrophilic cellulose in thermoplastic composites leads to aggregation of cellulose therein. Further, natural fibres such as cellulose generally have high moisture/water absorption properties that limit potential use in certain applications, such as in hydrophobic polymer matrices.
In the paper-making industry, high amounts of energy are typically required to fiberize pulp as pulp generally possesses strong inter-fiber hydrogen bonding. To reduce energy costs, efforts have been made to reduce hydrogen bonding among fibres in pulp lower the fiberization energy requirement during paper-making by adding organic and/or inorganic chemicals called debonders. Typically, debonders that have been used for this purpose are surfactants (e.g. substances that tends to reduce the surface tension of a liquid in which it is dissolved).
Accordingly, there is a need for improved systems and methods for the dispersion of cellulose-based fibres such as Cellulose Filaments in thermoplastic matrices as a high dispersion of cellulose-based fibres in thermoplastic matrices is needed to obtain well-defined mechanical properties of resulting composite materials.